U.S. patent number 5,810,755 [Application Number 08/710,229] was granted by the patent office on 1998-09-22 for medicated wound dressing.
Invention is credited to Eric G. LeVeen, Harry H. LeVeen, Mary Louise LeVeen, Robert F. LeVeen.
United States Patent |
5,810,755 |
LeVeen , et al. |
September 22, 1998 |
Medicated wound dressing
Abstract
A wound dressing, suitable for use in protecting an open wound
or burned tissue from direct exposure to air and capable of
maintaining an aqueous environment of wounded tissue with which it
is in brought into contact is comprised of a hydrophilic, yet
insoluble material, advantageously a polymeric compound capable of
being reversibly complexed with elemental iodine, thereby
permitting release of therapeutic amounts of free iodine into a
wound with which it is brought in contact. As a shaped mass of
pliable and absorbent material, such a polymeric foam, such
dressing is particularly suited for application to fresh and
infected burns and open wounds. When alternatively configured as a
hydrophilic film complexed with free iodine for use as a surgical
drape, in addition to providing a barrier against direct exposure
to air, such dressing is bacteriocidal, preventing infection of the
wound from airborne contaminants in the operating room.
Inventors: |
LeVeen; Harry H. (Charleston,
SC), LeVeen; Mary Louise (Charleston, SC), LeVeen; Eric
G. (Charleston, SC), LeVeen; Robert F. (Omaha, NE) |
Family
ID: |
23263734 |
Appl.
No.: |
08/710,229 |
Filed: |
September 12, 1996 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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324471 |
Oct 17, 1994 |
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Current U.S.
Class: |
602/48; 424/447;
424/448; 602/46; 604/265; 604/890.1 |
Current CPC
Class: |
A61F
13/023 (20130101); A61F 2013/00523 (20130101) |
Current International
Class: |
A61F
13/02 (20060101); A61F 13/00 (20060101); A61F
013/00 () |
Field of
Search: |
;602/42,43,46,48,53,54,56,58,59
;604/304,306,307,265,890.1,891.1,892.1 ;128/846-847,849,888
;424/445-449 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
LeVeen et al., The Mythology of Providone-Iodine and the
Development of Self Sterilizing Plastics, Surgery, Gynecology &
Obstetrics, Feb. 1993, vol. 176, pp. 183-190..
|
Primary Examiner: Buiz; Michael Powell
Assistant Examiner: Smith; Chalin
Attorney, Agent or Firm: Ruschmann; Herbert F. Wechsler;
Lawrence W.
Parent Case Text
REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No.
08/324,471 filed Oct. 17, 1994 entitled A WOUND DRESSING, now
abandoned.
Claims
What is claimed is:
1. A wound dressing comprising:
a shaped mass of a material, said material being included in a
class capable of complexing with iodine, yet possessing reversible
binding sites to allow release of free iodine in therapeutic
concentrations;
said shaped mass being sufficiently complexed with free iodine to
render it bactericidal, virucidal, and fungicidal;
said shaped mass including a wound contact surface, said wound
contact surface including non-irritating surface configuration
suitable for application to a wound site and a surface opposite
said wound contact surface defining an outwardly disposed
surface;
a fluid permeable film coating disposed on said outwardly disposed
surface and attached thereto; and
a fluid impermeable film attached peripherally to said fluid
permeable film coating disposed such that said fluid permeable film
is interposed between said outwardly disposed surface and said
fluid impermeable film, a combination of said fluid permeable film
and said fluid impermeable film forming an envelope structure into
which medicants are disposable without requiring removal of said
wound dressing from said wound site, said fluid permeable film
coating permitting passage of said medicants from said envelope to
said shaped mass for absorption thereby.
2. A wound dressing as in claim 1, wherein said material is an open
cell hydrophilic polyurethane foam.
3. A wound dressing as in claim 1, further comprising an organic
polybasic acid for acidifying said shaped mass.
4. A wound dressing as in claim 1, wherein said material is a
partially cross-linked polyalcoholic foam.
5. A wound dressing as in claim 1, wherein said material is a
partially cross-linked polyvinyl alcohol polymer.
6. A wound dressing as in claim 1, wherein said material is a
partially cross-linked cellulose polymer.
7. A wound dressing as in claim 1, wherein said material is
acidified by one of an organic polybasic acid and a
polycarboxylated polyvinyl resin.
8. A wound dressing as in claim 1, further comprising an entry flap
permitting access to said reservoir and having a reclosable contact
adhesive for sealing said reservoir.
9. A wound dressing as in claim 1, further comprising said
reservoir being sealed and allowing said medicant to be disposed
therein by means of a needle syringe.
10. A wound dressing, comprising:
a shaped mass of a pliable and absorbent material, said shaped mass
including a wound contact surface of non-irritating surface
configuration suitable for application to a wound site and a
surface opposite said wound contact surface defining an outwardly
disposed surface;
a fluid permeable film coating disposed on said outwardly disposed
surface and attached thereto; and
a fluid impermeable film attached peripherally to said fluid
permeable film coating disposed such that said fluid permeable film
is interposed between said outwardly disposed surface and said
fluid impermeable film, a combination of said fluid permeable film
and said fluid impermeable film forming an envelope structure
defining reservoir into which medicants are disposable without
requiring removal of said wound dressing from said wound site, said
fluid permeable film coating permitting passage of said medicants
from said reservoir to said shaped mass for absorption thereby.
11. A method for treating externally damaged tissue,
comprising:
applying a dressing to said damaged tissue, said dressing including
a shaped mass of material, said material being included in a class
capable of complexing with iodine, yet possessing reversible
binding sites to allow the release of free iodine in therapeutic
concentrations, said material having iodine complexed therewith,
said shaped mass including a contact surface and an outwardly
disposed surface opposite said contact surface;
disposing said dressing with said contact surface in contact with
said damaged tissue;
permitting said dressing to remain in said contact with said
damaged tissue over a period of time, said therapeutic
concentrations of free iodine being released to said damaged tissue
over said period of time of such contact; and
adding a quantity of iodine solution to said shaped mass via said
outwardly disposed surface while said dressing remains in said
contact with said damaged tissue to replenish an amount of said
iodine complexed with said material which is depleted by release of
said therapeutic concentrations of free iodine to said damaged
tissue over a portion of said period of time.
12. A wound dressing as in claim 11, wherein said material is a
partially cross-linked polyalcoholic foam.
13. A wound dressing as in claim 11, wherein said material is a
partially cross-linked polyvinyl alcohol polymer.
14. A wound dressing as in claim 11, wherein said material is a
partially cross-linked cellulose polymer.
15. A wound dressing as in claim 11, wherein said material is
acidified by one of an organic polybasic acid and a
polycarboxylated polyvinyl resin.
16. The method according to claim 11, wherein said dressing further
includes a fluid permeable film coating disposed on said outwardly
disposed surface and attached thereto, and a fluid impermeable film
sealably attached peripherally to said fluid permeable film coating
disposed such that said fluid permeable film is interposed between
said outwardly disposed surface and said fluid impermeable film, a
combination of said fluid permeable film and said fluid impermeable
film forming an envelope structure defining a reservoir into which
medicants are disposable without requiring removal of said wound
dressing, and said fluid permeable film coating permitting passage
of said medicants from said reservoir to said shaped mass for
absorption thereby.
17. The method according to claim 16, wherein said material is a
hydrophilic open cell polyurethane foam, and said fluid permeable
film coating is bondingly attached to said shaped mass.
18. A wound dressing as in claim 16, further comprising an entry
flap permitting access to said reservoir and having a reclosable
contact adhesive for sealing said reservoir.
19. A wound dressing as in claim 16, further comprising said
reservoir being sealed and allowing said medicant to be disposed
therein by means of a needle syringe.
20. A method for treating externally damaged tissue,
comprising:
providing a dressing including a shaped mass of material, said
shaped mass including a contact surface and an outwardly disposed
surface opposite said contact surface, a fluid permeable film
coating disposed on said outwardly disposed surface and attached
thereto, and a fluid impermeable film sealably attached
peripherally to said fluid permeable film coating disposed such
that said fluid permeable film is interposed between said outwardly
disposed surface and said fluid impermeable film, a combination of
said fluid permeable film and said fluid impermeable film forming
an envelope structure defining a reservoir into which medicants are
disposable without requiring removal of said wound dressing, and
said fluid permeable film coating permitting passage of said
medicants from said reservoir to said shaped mass for absorption
thereby;
disposing said dressing with said contact surface in contact with
said damaged tissue and disposing said medicants in said reservoir;
and
permitting said dressing to remain in said contact with said
damaged tissue over a period of time, and replenishing said
medicants in said reservoir to replace amounts released to said
damaged tissue over said period of time of such contact.
Description
BACKGROUND OF THE INVENTION
The incidence of infection of wounds is generally dependant upon
the causative factors, and the type and extent of damage to the
skin. Wounds resulting from accidental causes are exposed to
environmental contaminants, and are therefore invariably subject to
later infection. When such injury occurs outdoors, these so called
"dirty wounds" are particularly prone to infection because of the
high level of contamination. When wounds are denuded of overlying
skin there is an additional tendency towards infection from
airborne contamination. When a significant amount of underlying
tissue is exposed, a risk of infection may exist even in clean
environments, such as operating rooms.
It has been shown that the incidence of infection, even in clean
operative wounds, is directly proportional to the length of time
that the tissues are exposed to air. Drying of the tissue during
long periods of exposure devitalizes it, lowering resistance of the
contaminated tissue to infection. Another factor detrimental to the
healing of open wounds, is the loss of carbon dioxide to the air
from the wound's surface. Such loss produces a respiratory
alkalosis in the local tissue, leading to an alkaline shift in the
pH. This results in an undesirable shift of the
hemoglobin/oxyhemoglobin dissociation curve, which in turn
stabilizes the oxyhemoglobin, and inhibits its conversion to
reduced hemoglobin at reduced oxygen tensions (known as the Bohr
effect). Thus, as noted in an article by LeVeen, H. et al., Ann
Surg 148: pp 745-753(1973), incorporated herein by reference for
its relevant teachings regarding this effect, wounds are desirably
maintained at a relatively acid pH, whereby the oxygen tension is
raised.
Various products have been developed, intended to discourage
infection when topically applied. Antibiotics, and preparations
containing silver salts or sulfonamide compounds, for example, have
been used with some success. However, some wounds, for example
those the result of burns, often become infected notwithstanding
such preventative application. Various prior art wound dressings
have also been developed to address the need to prevent wound
infection, but have not heretofore demonstrated the required
effectiveness.
Iodine has been used advantageously to treat wounds and prevent
infection, by virtue of its germicidal, algaecidal, sporicidal,
amoebacidal, myocidal, virucidal and bacteriocidal properties. To
be effective, however, treatment of the wound or burn with iodine
must continue essentially uninterrupted, heretofore requiring
continual and repeated application of the iodine to the wound site
at regular intervals.
During surgery, exposure to airborne contaminants is a problem
contributing to infection of the patient, particularly during such
procedures as vascular grafts, in which there is evidence that
contamination often occurs to the exposed tissues of the skin
during preparation of the graft. Sterile drapes, for example of the
type offered by 3M Corporation under the trade name IOBAN, are
presently used as a type of wound dressing, to cover wound sites
during surgical procedures. These drapes are generally comprised of
a film material, and are coated on the wound contact side thereof
with a contact cement which may contain iodine. The iodine, so
contained in the contact cement, is not transferable through the
film barrier, and therefore does not offer the necessary protection
from airborne contaminants.
It is known that free, or elemental iodine in concentrations of as
low as one part per million (1 ppm) is sufficient to kill many
bacteria. It has been shown clinically, for example, that a saline
flush containing 2 ppm of free iodine was sufficient to prevent
peritonitis in patients receiving peritoneal dialysis as a
treatment for renal failure. Stephen RL et al., Dialysis and
Transplant, 1979, 8:pp 584-655. An iodine/saline flush has also
proved curative in other cases of peritonitis not related to
dialysis. Furthermore, in these concentrations, iodine has been
shown to be non-irritating, even when placed directly in the eye in
the form of a 2 ppm iodine/saline wash. Id.
These authors, Stephen et al., state that the saline washed away
glucose which would otherwise tend to convert free iodine to
inactive iodine. Subsequent studies have indicated that rather than
the 2 ppm shown effective in a saline solution, a higher
concentration of between about 5 and 10 ppm of free iodine is
believed to be required where glucose and protein are not flushed
away. In such concentration, the iodine has been found to be
bacteriocidal, virucidal, and fungicidal, and non-inflammatory and
non-irritating to tissue.
Use of a lightly cross-linked polyurethane which has been complexed
with free iodine has been suggested as a means by which iodine may
be released in therapeutic concentrations when exposed to an
aqueous environment. Known as a type of iodophor, use of such
iodine complexed polyurethane is disclosed in U.S. Pat. No.
4,381,380 issued to LeVeen et al., and for purposes of rendering
objects made from the material bacteriocidal, virucidal, and
fungicidal.
Further U.S. Pat. Nos. 5,000,749, 5,070,889, and 5,156,164 issued
to LeVeen et al., expanded the use of such an iodophor to treating
external tissue. As disclosed therein, an open cell polyurethane
sponge was shown effective in treating and preventing vaginitis
when complexed with iodine and used as a tampon. However effective
in treating undamaged external tissue, the prior art does not offer
guidance on the effectiveness or negative indications of using such
an iodophor in direct contact with an open wound or burn.
It would therefore be desirable to provide a wound dressing,
suitable for use in protecting an open wound or burned tissue from
direct exposure to air for the reasons described above, and which
is capable of maintaining an aqueous environment, permitting the
release of medicants, including antiseptics such as iodine, into
the wounded tissue with which it is in contact. When configured and
used as a surgical drape, in addition to providing a barrier
against direct exposure to air, such dressing would also be
bacteriocidal, preventing infection of the wound from airborne
contaminants in the operating room.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a wound
dressing which overcomes the drawbacks of the prior art.
It is a further object of the invention to provide a wound dressing
which protects wounds, including those resulting from burns, from
infection, by preventing drying at the protected site, and by
maintaining the wound at a relatively acid pH.
It is a still further object of the invention to provide a wound
dressing which is hydrophilic, and which is capable of releasing
therapeutically effective amounts of free iodine to the wound over
prolonged periods.
It is yet a further object to provide a wound dressing which may be
replenished when medicants contained therein are depleted, without
requiring removal from contact with the wound.
Briefly stated, the present invention provides a wound dressing
comprised of a of hydrophilic, yet insoluble material,
advantageously a polymeric compound capable of being reversibly
complexed with elemental iodine, thereby permitting release of
therapeutic amounts of free iodine into a wound with which it is
brought in contact. Such polymeric compound may include such
substances as polyurethane or other plastics, for example those
which are the result of cross-linking polyalcohols. Such alcohols,
include for example, glycerol, and other polyalcohols of high
molecular weight, such as polyvinyl alcohol (PVA) polymers and
cellulose polymers. Polyvinyl alcohol polymers are water soluble at
all commercially available molecular weights from 25,000 to 100,000
and can be easily cross-linked to any desired molecular size and
degree. By lightly (i.e. partially) cross-linking the polyalcohols,
the resultant compound is hydrophilic, and retains reversible
binding sites to which iodine may attach and be complexed
therewith. PVA is easily cross-linked with a suitable cross-linking
agent, including, for example, formaldehyde, glyoxal,
glutaraldehyde, or diisocyanate, to form water insoluble compounds
of high molecular weight. The dressing will generally be of a
flattened and pliable, bandage-like configuration, although the
precise physical characteristics, including size, shape, thickness,
flexibility, etc. will depend upon the particular nature and extent
of the wound, and its position on the body. Additionally, the wound
dressing will include a non-irritating surface along a portion of
its external surface which is specifically intended to come in
direct contact with the wound, referred to herein as the "contact
surface". In accordance with an embodiment of the invention, a
wound dressing is comprised of a shaped mass of absorbent material,
conveniently a non-irritating, hydrophilic, open cell foam. The
foam or other suitable absorbent material is advantageously capable
of complexing with iodine, and has reversible binding sites which
permit release of therapeutically effective amounts of iodine into
an aqueous environment. The material may be, for example,
polyurethane, or a partially cross-linked polyalcoholic foam, as
described above, or any other suitable material demonstrating the
aforementioned desired properties. When placed in contact with a
wound, the absorbent material serves to absorb fluids exuded from
the injured tissue, keeping the covered wound moist, while
continually releasing iodine into the wound in quantities that are
bacteriocidal, yet non-irritating.
In a further embodiment directed primarily to treatment of wounds
in which the tissue will remain open for prolonged periods, the
wound dressing comprised of the absorbent material as described
above is optionally covered with a film on a surface portion of the
wound dressing not in contact with the wound site, referred to
herein as the "outwardly facing surface". The film is
advantageously impermeable to fluids, particularly aqueous fluids,
to inhibit fluid loss to the ambient surroundings, and prevent
soiling of the dressing by environmental contaminants. Where the
absorbent material is a polyurethane foam, the film is
advantageously a type bondable thereto.
In another embodiment, means are provided on the wound dressing
which permit the infusion of medicants into the shaped absorbent
mass to replace those depleted during use, without requiring
removal of the dressing from the wound site. This feature is
conveniently provided in the form of an enclosed envelope structure
comprised of film, disposed on the surface portion of the wound
dressing which is outwardly disposed when the dressing in contact
with the wound. The envelope film, attached to and in direct
overlaid contact with the absorbent material, is permeable to
fluids, by virtue, for example, of perforations formed therein. The
remaining film forming the envelope structure and not in direct
contact with the shaped mass of the dressing is fluid impermeable,
such that when a medicant is instilled into the envelope which
serves as a reservoir, it seeps into the absorbent dressing
material through the fluid permeable film layer interposed between
the shaped mass and the outermost fluid impermeable film layer,
replacing medicants, such as iodine, passing from the dressing into
the wound.
In yet another embodiment, the wound dressing is in the form of a
surgical drape, comprised of a hydrophilic film, and which may be
adhered to skin to prevent contamination from airborne contaminants
in, for example, an operating room. Such a drape would be comprised
of polyurethane film, or other suitable film substance capable of
reversibly complexing with elemental iodine.
The above, and other objects, features and advantages of the
present invention will become apparent from the following
description read in conjunction with the accompanying drawings, in
which like reference numerals designate the same elements.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side cross-sectional view of an embodiment of a wound
dressing in accordance with the invention particularly suited for
prolonged use; and
FIG. 2 is a side cross-sectional view of another embodiment of a
wound dressing in accordance with the invention, and which permits
replenishment of medicants without requiring removal of the
dressing from the wound site .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention provides a wound dressing comprised of a
hydrophilic, yet insoluble material, advantageously a polymeric
compound capable of being reversibly complexed with elemental
iodine, thereby permitting release of therapeutic amounts of free
iodine into a wound with which it is brought in contact. Such
polymeric compound may include such substances as polyurethane or
other plastics, for example those which are the result of
cross-linking polyalcohols. Such alcohols, include for example,
glycerol, and other polyalcohols of high molecular weight, such as
polyvinyl alcohol (PVA) polymers and cellulose polymers. Polyvinyl
alcohol polymers are water soluble at all commercially available
molecular weights from 25,000 to 100,000 and can be easily
cross-linked to any desired molecular size and degree. By lightly
(or partially) cross-linking the polyalcohols, the resultant
compound is hydrophilic, and retains reversible binding sites to
which iodine may attach and be complexed therewith. PVA is easily
cross-linked with a suitable cross-linking agent including for
example formaldehyde, glyoxal or glutaraldehyde to form water
insoluble compounds of high molecular weight. The precise physical
characteristics, including size, shape, thickness, flexibility,
etc. will depend upon the nature and extent of the wound, and its
position on the body. In general, however, such wound dressing will
include a non-irritating surface along a portion of its external
surface which is specifically intended to come in direct contact
with the wound and surrounding tissue, referred to herein as the
"contact surface". Also for purposes herein, the remaining external
surface not intended to contact the patient will be referred to as
the "outwardly facing surface".
In accordance with an embodiment of the invention, a wound dressing
is provided in the form of a shaped mass, conveniently comprised,
for example, of a non-irritating, hydrophilic, open cell foam.
Regardless of the material selected for the shaped mass, the
material should advantageously be absorbent, pliable and present a
wound contact surface which is non-irritating to the wound site
with which it is to be brought in contact. The material should also
advantageously be capable of complexing with iodine, and contain
reversible binding sites which permit release of therapeutically
effective amounts of iodine into an aqueous environment. Studies
conducted in conjunction herewith have indicated that the incidence
of infection can be sharply reduced or prevented in contaminated
open wounds, even those containing devitalized tissue, by the
application, advantageously immediately following the time of
injury or as soon thereafter as permitted, of such iodine complexed
dressing, thus advancing the concept of employing a complexed
iodophor for its bacteriocidal properties, to treatment of open
wounds and burns.
The material from which a suitably shaped dressing is fabricated
may be, for example, polyurethane, or a partially cross-linked
polyalcoholic foam, as outlined above, or any other suitable
material demonstrating the aforementioned desired properties. It is
further noted that although an open cell foam is conveniently
employed, other suitable material exhibiting like properties
mentioned as advantageous to the invention may be substituted
without departure from the intended scope herein. For example, the
shaped mass may be a fibrous or woven pad made of the
aforementioned materials or other suitable compounds. When placed
in contact with a wound, the dressing material advantageously
serves to absorb fluids exuded from the injured tissue, keeping the
covered wound moist, while continually releasing iodine into the
wound in quantities that are bacteriocidal, yet non-irritating.
Detailed examples of suitable polyurethane compounds to be used for
this embodiment and for any subsequently described embodiments
herein which include an iodine complexed hydrophilic material for
releasing therapeutically effective concentrations of iodine in an
aqueous environment may be found in U.S. Pat. Nos. 4,381,380,
5,000,749, 5,070,889, and 5,156,164 issued to LeVeen et al., which
are incorporated herein by reference for their teachings regarding
the characteristics of the polyurethane foam, effective amounts of
iodine, methods for complexing the foam dressing material with
iodine, and any additional subject matter contained therein
relevant to the invention disclosed herein.
As noted, in accordance with the above described embodiment of the
invention, any material demonstrating suitable characteristics, for
example, any hydrophilic, open celled foam capable of complexing
sufficiently with iodine to release therapeutically effective
concentrations of free iodine, may be used in addition to
polyurethane foam. For example, a foamed solid hydrophilic
polyalcoholic plastic can be complexed with iodine typically by
immersion in an aqueous solution of iodine containing iodides. For
purposes herein, it is generally desirable to select a foam or
other suitable material which is insoluble in water but which
demonstrates an affinity to water, i.e. hygroscopic
characteristics. As already noted, PVA foams sparingly cross-linked
with formaldehyde, diisocyanate or other suitable cross-linking
agents, form polyalcoholic plastics which are water insoluble but
very hygroscopic. While being water insoluble, these cross-linked
compounds all retain a strong affinity for water. Like cellulose
sponges commonly used in kitchens and bathrooms, most of these
foams are rigid in their dry form in contrast to hygroscopic open
cell polyurethane foams which remain soft and pliable in the dry
state. Water, however, plasticizes them, making them soft and
flexible. One such foam of lightly cross-linked PVA is commercially
available, for example, as manufactured and sold under the trade
name of Ivalon sponge for medical applications by Unipoint
Industries, Inc., 120 Transit Avenue, Thomasville, N.C. 27360. PVA
sponges have a great affinity for dissolving iodine. Such sponges
can be iodinated, for example, by aqueous iodine solutions
containing iodides such as Aqueous Iodine Solution (USP), which is
a 2% solution of iodine in a 2.6% solution of sodium iodide. When
PVA sponge is dipped into this iodine solution, the sponge turns
dark purple. The sponge is then washed and compressed repeatedly in
running deionized water to remove all traces of iodide and any
excess iodine. The iodinated cross-linked PVA foams readily
dissolve iodine and since iodine is relatively insoluble in water,
(0.0013 moles of iodine dissolve in 1 liter of water at 25.degree.
C.) a partition coefficient is set up between the concentration of
iodine in the sponge and the concentration of free iodine in the
water. In addition, sulfates may be used to decrease the solubility
of free iodine in water to non-irritating concentrations. This
partition coefficient is proportional to the degree of loading in
the sponge and can be adjusted to establish any desired initial
free iodine concentration in body fluids, for example, by varying
exposure time and concentration of immersion solution. We have
found that a initial free iodine concentration between 5 and 50
parts per million to be ideal. However, in the presence of blood or
protein this level can be safely adjusted to as high as 100 ppm. In
the preferred case, such sponges are applied to wounds in their
moistened form, containing physiological saline solution. (0.9%
sodium chloride dissolved in distilled water). The dressing may be
packaged in such moistened state, ready for application.
Regardless of what material is selected for the shaped mass of the
dressing, complexing with iodine is accomplished in a like manner.
As described above, iodine complexing may be typically
accomplished, for example, by dipping the dressing in an aqueous
iodine solution containing iodides such as Aqueous Iodine Solution
(USP), which is a 2% solution of iodine in a 2.6% solution of
sodium iodide. The foam or like material is immersed in this
solution with compression to dispel any entrapped air. When fully
saturated with the solution, the dressing is removed and again
compressed to expel any residual iodine solution, and is then
transferred to running deionized water and repeatedly compressed to
purge any sodium iodide and unattached iodine. This is continued
until the effluent is clear. The dressing is then air dried. For
prolonged storage prior to use, the iodinated dressing described in
the present and any subsequent iodine complexed embodiments may
optionally be placed in a sealed, air-tight package to prevent
sublimation which would otherwise occur due to the vapor pressure
of iodine.
In a further embodiment, the shaped mass of the dressing is
acidified by treatment with an organic polybasic acid or a
polycarboxylated polyvinyl resin. This serves to advantageously
raise the pO.sub.2 of ischemic tissue, to promote healing. The
dressing material may be so treated, for example, by placement in a
4% aqueous solution of such polycarboxylated polyvinyl resin,
available for example from B. F. Goodrich under the trade name
CARBOPOL. When such acidification of the dressing is performed in
advance of application to the wound, and the resin allowed to dry
in the shaped mass, the dressing material should be moistened with
normal saline solution prior to application to the wound.
A further embodiment is directed primarily to treatment of wounds
in which the tissue will remain open for prolonged periods.
Referring to the figures, and in particular FIG. 1, a wound
dressing as described in the preceding embodiments, generally
designated 10, and shown in contact with a wound W, includes a
shaped mass 11 presenting an exterior surface configuration
comprised of a wound contact surface 11a and an outwardly facing
surface 11b. Outwardly facing surface 11b, i.e. the external
surface not brought into direct contact with the wound W or
surrounding tissue, is covered with a film 12. Film 12 is
advantageously impermeable to fluids, particularly aqueous fluids,
to inhibit fluid loss to the ambient surroundings, and prevent
soiling of shaped mass 11 by environmental contaminants. Where
shaped mass 11 is a polyurethane foam, film 12 is advantageously a
type bondable thereto.
Another embodiment, depicted in FIG. 2, permits the infusion of
medicants into a dressing to replace those depleted during use,
without requiring removal of the dressing from the wound site. A
dressing, generally designated 20, and shown in contact with a
wound W, includes a shaped mass 21 presenting an exterior surface
configuration comprised of a wound contact surface 21a and an
outwardly facing surface 21b. Means are provided, conveniently in
the form of an enclosed envelope structure 22 comprised of film,
fixed to outwardly disposed surface 21b of shaped mass 21, for
retaining medicants instilled therein. The film envelope 22 is
comprised of a fluid permeable layer 22a attached to, and in direct
overlaid contact with, outwardly disposed surface 21b of shaped
mass 21. Such fluid permeability may be accomplished conveniently,
for example, by creation of a plurality of perforations in an
otherwise fluid impermeable film. The remaining film which forms
film envelope structure 22, and not in direct contact with shaped
mass 21, is a fluid impermeable layer 22b. Fluid permeable layer
22a and fluid impermeable layer 22b are peripherally sealed to one
another over sufficient edge portions 24 to permit retention of
fluid medicants placed therebetween. For example, where shaped mass
21 and film envelope 22 are rectangular, fluid permeable layer 22a
and fluid impermeable layer 22b are advantageously sealed along at
least three sides to form a pocket-like configuration. By virtue of
such structure, medicants may be instilled into the film envelope
22, which serves as a reservoir, from where they can then seep into
shaped mass 21 through fluid permeable layer 22a disposed in a
position interposed between shaped mass 21 and outermost fluid
impermeable layer 22b, thereby replacing depleted medicants passing
from the dressing into the wound. The degree of fluid permeability
of fluid permeable layer 22a determines the rate at which fluid
instilled into and contained within film envelope 22 is absorbed by
shaped mass 21, thereby providing means for regulation of the
medicant fluid uptake of shaped mass 21. Optionally, envelope
structure 22 may include an entry flap 23 disposed along an upper
edge thereof, scalable by for example reclosable contact adhesive.
Many other alternative envelope configurations are envisioned,
including for example a completely sealed envelope 22 into which
medicants are instilled by use of a needle syringe in much the way
contents of a ringer bag are currently accessed.
The embodiment depicted in FIG. 2 is useful for replenishment of
any desired medicant, including germicidal material such as, for
example, chlorhexadine gluconate, or chemotherepeutic agents for
application to malignant ulcerations. Furthermore, the embodiment
may be used particularly advantageously for replenishing iodine,
where shaped mass 21 is a suitable material complexed with iodine,
such as, for example, polyurethane foam. Following application of
dressing 20 to wound site W, as iodine is released in
therapeutically effective amounts to the moist wound, there is a
color change from brown, to the original white color of the foam
when the complexed iodine is completely exhausted. Upon such
depletion, dressing 20 may be rejuvenated without requiring removal
of same from the patient. Iodine instilled into film envelope 22
seeps into shaped mass 21 at a rate regulated by the permeability
of fluid permeable layer 22a, complexing with the polyurethane foam
or other suitable material of which it is comprised.
Suitable hydrophilic materials complexible with iodine and
applicable to the above described embodiments are available from a
variety of sources. For example, hydrophilic prepolymers are
available from Hampshire Chemical Corporation, 55 Hayden Avenue,
Lexington, Mass. 02173 under the trade name HYPOL. These
prepolymers merely require the addition of water to form a
hydrophilic open cell foam when mixed in the recommended manner.
Premolded polyurethane foam is also available from Avitar, Inc.,
250 Turnpike Street, Canton, Mass. 02021 and from E. N. Murray
Company, Inc., 280 Boone Court, Plano, Tex. 75203. Extruded
polyurethane foam, which is very hydrophilic and also suitable for
use in accordance with the intended scope of the invention, is
available from Madison Polymeric Engineering, 495 Ward Street Ext.,
Wallingford, Conn. 06492.
In accordance with a further embodiment of the invention, a wound
dressing takes the form of a surgical drape, comprised of a
hydrophilic film, and which may be adhered to skin to prevent
contamination from airborne contaminants in, for example, an
operating room. Such a drape is comprised of polyurethane film, or
other suitable film substance capable of reversibly complexing with
elemental iodine. It is noted that even highly cross-linked
thermoset polyurethane complexes sufficiently with iodine to
release iodine in quantities sufficient to establish an equilibrium
of 5-10 ppm of free iodine in an aqueous medium, dependant on the
degree of loading of the polyurethane.
The drape described above which provides a bacteriocidal barrier
may be fabricated, for example, from a polyurethane film of desired
widened dimensions, which is subsequently dipped in 2% aqueous
iodine dissolved in 2.6% aqueous sodium iodide solution. The excess
iodine solution is removed by passing the film through a ringer
into a bath of continually changed deionized water. Washing is
continued until the effluent is clear. The film is again passed
through a ringer and air dried. When dry, one side of the film is
coated with a contact cement suitable for use on human skin. Many
such adhesives are available from The 3M Corporation and other
companies serving the adhesive plaster market. The film is then
adhered to a releasing film, and advantageously packaged to exclude
air and extent shelf life. Although the drape need not be
sterilized by virtue of the iodine contained therein, if so
desired, such may be accomplished be exposure to gamma irradiation.
Suitable hydrophilic films may be obtained, for example, from JPS
Elastomerics Corp., 395 Pleasant Street, Northhampton, Mass.
01061-0658, or Miles Inc., Mobay Road, Pittsburgh, Pa.
15205-9741.
Having described preferred embodiments of the invention with
reference to the accompanying drawings, it is to be understood that
the invention is not limited to those precise embodiments, and that
various changes and modifications may be effected therein by one
skilled in the art without departing from the scope or spirit of
the invention as defined in the appended claims.
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